With CuKa radiation it is possible to use the anomalous signal to find
Calcium. Just scale your integrated intensities together keeping your
Friedel mates apart, and make an anomalous map using the phases from
your model. Atoms like S and Ca stand out very well, doesn't help with
Na though.
Steven Weigand mailto:steve at xray1.pharm.nwu.edu
Dept. Mol. Pharm. Biol. Chem. -- S215 Lab phone: (312) 503-0813
Northwestern University Medical School
303 East Chicago Ave. Chicago, IL 60611